WASHINGTON

US President Donald Trump is "really pleased" with the progress made towards an agreement on a Ukraine peace deal during talks in Europe, a US official said Monday.

The official, who was one of two who participated in the negotiations that began Sunday and briefed reporters on their progress, said "literally 90% of the issues between Ukraine and Russia" have been resolved, but acknowledged that "there's some more things that have to be worked out."

"We've moved considerably closer in narrowing the issues between the Ukrainians and the Russians. That's clear," the official, who briefed reporters on condition of anonymity to discuss the ongoing talks, said. "We've got multiple different solutions to bridge the gap between the parties that we're suggesting to them."

The other official said the basis of security guarantees that will be provided to Ukraine under the terms of a peace deal are "Article Five-like" assurances for Kyiv that will serve as "very strong deterrence." He was referring to NATO's collective defense article.

"The Europeans expressed a lot of appreciation for President Trump's willingness to lean into this issue and to offer such guarantees. Those guarantees will not be on the table forever. Those guarantees are on the table right now, if there's a conclusion that's reached in a good way, and President Trump's very focused on reaching a conclusion to this conflict that really stops the Russians from moving west," the official said.

Trump "is willing" to put the security guarantees before the Senate for ratification, "and that was, I think, a particular surprise to Ukrainians and Europeans," the other official added.

Ukrainian President Volodymyr Zelenskyy on Sunday said bilateral security guarantees with the US, Europe, and other countries are a “compromise” in lieu of Ukraine’s NATO accession.

The comments mark a major shift in Kyiv’s approach to membership in the transatlantic alliance, an ambition that was enshrined in Ukraine’s Constitution in 2019.

Russia has voiced fierce opposition to Ukraine’s potential NATO membership, with President Vladimir Putin calling such a step a "direct threat" to Moscow's security just days before the start of the war in February 2022.

Trump "believes he can get Russia to accept" the Article Five-like assurances, the officials said.

While Russia has vocally opposed Ukraine's entrance into NATO, the second official said the Kremlin "has indicated they were open to Ukraine joining the EU, which would be the biggest expansion of the Euro free zone since the Berlin Wall."

The anonymous US officials said they would be participating in a dinner with Ukrainian and other European leaders, including Zelenskyy, to go over the progress made in talks, adding that Trump is expected to call into the gathering on Monday evening.

The US president has been briefed twice on the talks so far, one of the officials said.

Negotiators are expected to meet again this weekend, potentially in Miami, Florida, for further talks, according to the officials.